Author Topic: Hoag Type galaxies and Collisional rings  (Read 66890 times)

Thomas J

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Hoag Type galaxies and Collisional rings
« on: February 20, 2009, 01:25:51 pm »
Just out of interest, I would like to see how many of these rarities we can find and catalogue.

Please include an SDSS reference number with your post (A link is better)

The Hoag type is a ring galaxy named after the progenitor of the class; 'Hoags Object', discovered in 1950 by astronomer Arthur Allen Hoag.

The formation of this type is open to some debate; It may be through 'core instability' but more likely, it has formed from an accretion event some billions of years ago, when the galaxy was a spiral.

This event would suggest a collision or merge with a smaller galaxy passing through it's centre and creating a density wave pattern (think of dropping a pebble into a pool of water.)

As this circular wave propogates outward, stars are formed from the compressed material.

Title has been amended, see here http://www.galaxyzooforum.org/index.php?topic=273992.msg285684#msg285684

Here is Hoags object, courstesy of Hubble- NASA.


This is in the SDSS footprint, found by Alice, and posted previously by BL Lacertae

http://cas.sdss.org/astro/en/tools/explore/obj.asp?id=587739719767949555

Happy hunting and here is a link to Geoff Roynon's excelent Object of the Day regarding collisional rings
http://www.galaxyzooforum.org/index.php?topic=273672.0
« Last Edit: March 11, 2009, 07:11:36 pm by Thomas J »
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Pat

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Re: Hoag Types. Collisional rings?
« Reply #1 on: February 20, 2009, 01:27:54 pm »
Thomas, I think the scream  might well be one of these types of objects. Also isn't it cool about the other ringed galaxy in the upper right of the Hoag object!! :)  :o
« Last Edit: February 20, 2009, 01:34:22 pm by Pat »

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Lovethetropics

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Re: Hoag Types. Collisional rings?
« Reply #2 on: February 20, 2009, 01:32:56 pm »

 *and find lots of asteroids  ;D

elbereth

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Re: Hoag Types. Collisional rings?
« Reply #3 on: February 20, 2009, 01:34:35 pm »
that's a normal spiral galaxy, maybe starting to form a ring...

interesting... :)

Lovethetropics

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 *and find lots of asteroids  ;D

Lovethetropics

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 *and find lots of asteroids  ;D

milk_n_cookies

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Re: Hoag Types. Collisional rings?
« Reply #6 on: February 20, 2009, 01:47:08 pm »
actually got into a discussion regarding this one a couple weeks ago.



Thomas J

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Re: Hoag Types. Collisional rings?
« Reply #7 on: February 20, 2009, 01:51:39 pm »
All good for comparrison, IMO.

The bar type would suggest the 'bar instability' formation process for this one.
« Last Edit: March 06, 2009, 04:59:04 pm by Thomas J »
I am very interested in the Universe- I am specialising in the Universe and all that surrounds it.....            Peter Cook.


Thomas J

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Re: Hoag Types. Collisional rings?
« Reply #8 on: February 20, 2009, 01:52:35 pm »
that's a normal spiral galaxy, maybe starting to form a ring...

interesting... :)

Hi, Elbereth, welcome to the Zoo.
I am very interested in the Universe- I am specialising in the Universe and all that surrounds it.....            Peter Cook.


Thomas J

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Re: Hoag Types. Collisional rings?
« Reply #9 on: February 20, 2009, 01:56:59 pm »
Thomas, I think the scream  might well be one of these types of objects. Also isn't it cool about the other ringed galaxy in the upper right of the Hoag object!! :)  :o

I would tend to agree, Pat. :)
I am very interested in the Universe- I am specialising in the Universe and all that surrounds it.....            Peter Cook.


Thomas J

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Re: Hoag Types. Collisional rings?
« Reply #10 on: February 20, 2009, 02:05:04 pm »
A good candidate posted by SkippyG over in newbies

A possible overlapping star in this image

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jokergirl

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Re: Hoag Types. Collisional rings?
« Reply #11 on: February 20, 2009, 02:41:37 pm »


SDSS 587736976881418386

;)
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Thomas J

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Re: Hoag Types. Collisional rings?
« Reply #12 on: February 20, 2009, 03:05:30 pm »
I am very interested in the Universe- I am specialising in the Universe and all that surrounds it.....            Peter Cook.


Lovethetropics

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Re: Hoag Types. Collisional rings?
« Reply #13 on: February 20, 2009, 03:55:25 pm »
Tom, I have a question...does the ring have to be detached from the core to be a Hoag type?

 *and find lots of asteroids  ;D

Thomas J

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Re: Hoag Types. Collisional rings?
« Reply #14 on: February 20, 2009, 04:54:20 pm »
Tom, I have a question...does the ring have to be detached from the core to be a Hoag type?

I would say yes. It should be as close to Hoags Object as possible. :) ;)
I am very interested in the Universe- I am specialising in the Universe and all that surrounds it.....            Peter Cook.